The concrete panels are used in a wide range of applications in the civil engineering industry, the construction time being thus reduced. The pre-cast panels are manufactured by casting the concrete into forms (concrete forming. After hardening, the panels are vertically positioned at the construction site.
Since the panels are not insulated there is an disadvantage in insulating them at a later stage, as insulating operations are expensive and imply a lot of manual working.
Another disadvantage is they could not be used for ceilings, as they have not sufficient strength in the case of large-sized ceilings.
The patent US 2002017070 describes an expanded plastic module intended for the building of a concrete wall structure, insulated by interconnecting the modules and filling them with concrete. The module is made of expanded polystyrene. Each module has the form of a rigid block, having an interior configuration designed to be filled with concrete. Additionally, for the increase of strength, a network of steel or plastic bars is being introduced inside the modules. The disadvantage of this technical solution consists in a high rate of concrete consumption, flow problems upon the placing of concrete, due to the internal passages, positioned perpendicularly along the vertical and horizontal line; also, a too complex construction and additional manual working, brought about by the network of bars.
The patent WO 2005059264 relates to polyurethanes or polystyrene foams for concrete structures.
The insulating blocks elements have an interior arrangement in the form of vertical cavities in a trapezoidal, circular, elliptical or parabolic shape. The structure obtained after the blocks have been filled with concrete has good strength properties and optimum heat insulation; moreover, the strength of the linear structure is inferior to the structures in which concrete is cast in several directions.
The U.S. Pat. No. 4,942,707 describes ceiling or roof structures, based on a rigid insulation, provided with several cavities or passages that become molds for the concrete during its casting. Following the joining of structures in the form of a ceiling or a roof, concrete is to be cast in these cavities or passages. The disadvantage of this technical solution is the high rate of consumption of concrete; also, it may be applied only to ceilings and roofs.
Another major disadvantage of insulating elements with interior passages for casting of concrete is that they become only elements of a building, such as walls, ceiling, not being able to meet the necessary features for obtaining an appropriate supporting structure for a complete construction.